A pacemaker is a therapeutic physiological instrument that is adapted for connection to a patient through pacing electrodes. The pacemaker operates by providing a periodic electrical stimulus to the patient through the electrodes in order to maintain the patient's heartbeat. In the past, pacemakers have generally been internal (e.g., implantable), wherein the pacemaker electrodes are connected directly to the patient's heart. Prior external pacemakers have seen limited use, almost exclusively with unconscious patients, because of the pain associated with the delivery of a pacing stimulus through a patient's skin. It has not been uncommon for external pacing electrodes to produce crescent-shaped burns on a patient's skin adjacent the electrode edge when the electrodes were used over an extended period of time or with a high pacing current. There has therefore been a long-felt need for an improved electrode for external pacing that was suitable for use with a conscious patient and over an extended period of time.
To the extent that external pacing electrodes have been used in the past, they have generally been permanently attached to cables that are in turn attached to the pacemaker. To increase the versatility and usefulness of external pacing electrodes, it would be desirable to provide a disposable electrode having a small conductive terminal permanently affixed to the electrode, and to provide a connector whereby one end of the cable could be electrically connected to the terminal when pacing was required. Prior pacing electrodes have tended to avoid this approach, however, because of the difficulty in providing a connector that was easy to connect and disconnect but that was also sufficiently moisture proof for external pacing use.
A defibrillator is a therapeutic physiological instrument that is used to deliver an electric shock to a patient who is experiencing a cardiac arrythmia such as ventricular fibrillation. Such an electric shock frequently terminates the chaotic activity characteristic of an arrythmia, and restores the normal pumping action of the heart. Unlike pacemakers, many prior defibrillators have been designed for external use, wherein the electric shock is delivered to the patient via electrodes that contact the patient's skin through a layer of conductive gel or the like. The pain and burn factors associated with external pacemakers have generally not been a factor in limiting the use of external defibrillators, because defibrillation is only used for unconscious patients, because the use is intermittent rather than continuous, and because of the life-threatening nature of a cardiac arrythmia. Nevertheless, it would be an advantage to provide an improved defibrillator electrode in which the tendency to produce burns was not present.